Influence of Ceramic Dielectrics during Development of an Electrostatic Fine Particle Separator for the Combined Cycle with Pressurized Pulverized Coal Combustion (PPCC)

Project Number 265

Realization of the power plant concept with pressurized pulverized coal combustion (ppcc) needs a flue gas nearly free of particulate matter and alkali residuals with respect to gas turbine life cycle. Gas cleaning is done with a multi-stage molten ash separator. Current studies at the pilot plant of the ppcc-development project in Dorsten, Germany, show that the limit for safe turbine operation is now reached with the current particle separator (d_p < 3 µm; m_p < 3 mg/m_N³).

The scientific challenge of the project is to investigate the basic principles that lead to the observed particle reduction at the pilot plant in Dorsten and to develop a modelling tool for later optimization and scale up of the molten ash separator.

Thus, computational fluid dynamics (cfd)-modelling of the molten ash separator focuses on the calculation of the particle dynamics under ppcc-conditions. The modelling of electro-hydrodynamic interactions in the flue gas is object of the current investigations. The leading aspect is the use of electrical properties of the fine particles in combination with different ceramic collector materials at temperatures of about 1600 - 1700 K.

For determination of the boundary conditions for modelling and for validation of the models, a test facility was built which enables measurement of charging states of the fine particles and charge carrier emission of the ceramic components at temperatures higher than 1300 K.

The project is carried out by the Institute of Energy and Environmental Technology (IUTA) in Duisburg, Germany, and the Institute of Mechanical Process Engineering and Mechanics of the University of Karlsruhe, Germany, during the period from May 2004 to April 2006. The project is supported by VGB PowerTech e. V. through co-operation in the project committee and advanced from funds of the German BMWA by way of the Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AiF).